Call the police. If necessary, call the police in *his* home town.
Advice like this pisses me off because it's no advice at all. The police
won't do jack shit about this, it's a civil case. To the OP, since you paid
by MasterCard, dispute the charge when you get the bill. Of course
MasterCard will first ask that you try to work it out with the seller.
Have you asked the seller to take back the drive and refund your money? I
see nothing on the auction page that says as-is or no refunds, so you
should at least attempt to get a refund. Whatever you do, do not pay the
charge on your bill, write a letter to MasterCard briefly explaining the
situation. As long as the charge is in dispute, you won't be hit with
finance charges. Don't bother going to PayPal to resolve the issue, those
guys are a joke.